Biologists have successfully engineered algae to produce potential candidates for a vaccine that would prevent transmission of the parasite that causes malaria.
Initial proof-of-principle experiments suggest that such a vaccine could prevent malaria transmission.
The achievement could pave the way for the development of an inexpensive way to protect billions of people from one of the world’s most prevalent and debilitating diseases.
Malaria is a mosquito-borne disease caused by infection with protozoan parasites from the genus Plasmodium. It affects more than 225 million people worldwide in tropical and subtropical regions, resulting in fever, headaches and in severe cases coma and death.
While a variety of often costly anti-malarial medications are available to travellers in those regions to protect against infections, a vaccine offering a high level of protection from the disease does not yet exist.
The new development resulted from an unusual interdisciplinary collaboration between two groups of biologists at University of California, San Diego—one from the Division of Biological Sciences and San Diego Center for Algae Biotechnology, which had been engineering algae to produce bio-products and biofuels, and another from the Center for Tropical Medicine and Emerging Infectious Diseases in the School of Medicine that is working to develop ways to diagnose, prevent and treat malaria.
Part of the difficulty in creating a vaccine against malaria is that it requires a system that can produce complex, three-dimensional proteins that resemble those made by the parasite, thus eliciting antibodies that disrupt malaria transmission.
Most vaccines created by engineered bacteria are relatively simple proteins that stimulate the body’s immune system to produce antibodies against bacterial invaders. More complex proteins can be produced, but this requires an expensive process using mammalian cell cultures, and the proteins those cells produce are coated with sugars due to a chemical process called glycosylation.
“Malaria is caused by a parasite that makes complex proteins, but for whatever reason this parasite doesn’t put sugars on those proteins,” said Stephen Mayfield, a professor of biology at UC San Diego who headed the research effort.
“If you have a protein covered with sugars and you inject it into somebody as a vaccine, the tendency is to make antibodies against the sugars, not the amino acid backbone of the protein from the invading organism you want to inhibit. Researchers have made vaccines without these sugars in bacteria and then tried to refold them into the correct three-dimensional configuration, but that’s an expensive proposition and it doesn’t work very well,” he stated.
Instead, the biologists looked to produce their proteins with the help of an edible green alga, Chlamydomonas reinhardtii, used widely in research laboratories as a genetic model organism, much like the fruit fly Drosophila and the bacterium E. coli.
Zeenews India & PLoS ONE